Demonstration of human chorionic gonadotropin during the second half of the menstrual cycle in plasma of regularly menstruating women users of copper IUds.

An attempt has been made of demonstrating the beta subunit of HCG in the plasma of 13 regularly menstruating women wearing a copper IUD. Eighteen menstrual cycles were explored with a total of 94 specimens obtained at 3-day intervals starting from the 16th day of the cycle. A cross reaction with LH was excluded by simultaneous assay of this hormone. Progesteron was also assayed so as to exclude anovulatory cycles. Five out of 12 ovulatory cycles yelded positive results with HCG values ranging from 171 to 692 mIU per ml. We therefore agree with the hypothesis according to which copper IUDs do not interfere with fecundation but with subsequent stages, specifically about the time of nidation of the blastocyst in the uterus.